Embelin derivatives and their anticancer activity through microtubule disassembly.

Biological activities of the 1,4-benzoquinone derivatives 5- O-ethylembelin ( 1) and 5- O-methylembelin ( 2) were investigated. Both of them showed antiproliferative activity against a panel of human tumor cell lines upon comparison to normal marsupial kidney cells (PtK2). They arrested HL-60 cells in the G(0)/G(1) phase of the cell cycle in a dose- and time-dependent manner. In HeLa cells, exposure to 100 microM of 1 or 2 for 6 h induced a complete disassembly of the microtubule network and an increased number of cells blocked in mitotic stages. Treatment with 10 microM of 1 and 2 for 24 h induced apoptosis in HL-60 cells. This evidence suggests that both 1 and 2 are promising novel antimitotic and anticancer molecules targeting microtubular proteins.